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[150.101.137.139]) by mx.google.com with ESMTP id 62si156803ple.393.2019.03.28.14.21.50 for ; Thu, 28 Mar 2019 14:21:51 -0700 (PDT) Received-SPF: neutral (google.com: 150.101.137.139 is neither permitted nor denied by best guess record for domain of david@fromorbit.com) client-ip=150.101.137.139; Authentication-Results: mx.google.com; spf=neutral (google.com: 150.101.137.139 is neither permitted nor denied by best guess record for domain of david@fromorbit.com) smtp.mailfrom=david@fromorbit.com Received: from ppp59-167-129-252.static.internode.on.net (HELO dastard) ([59.167.129.252]) by ipmail02.adl2.internode.on.net with ESMTP; 29 Mar 2019 07:51:48 +1030 Received: from dave by dastard with local (Exim 4.80) (envelope-from ) id 1h9cT6-0008B9-11; Fri, 29 Mar 2019 08:21:48 +1100 Date: Fri, 29 Mar 2019 08:21:47 +1100 From: Dave Chinner To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 2/3] xfs: reset page mappings after setting immutable Message-ID: <20190328212147.GK23020@dastard> References: <155379543409.24796.5783716624820175068.stgit@magnolia> <155379544747.24796.1807309281507099911.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155379544747.24796.1807309281507099911.stgit@magnolia> User-Agent: Mutt/1.5.21 (2010-09-15) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 28, 2019 at 10:50:47AM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > The chattr manpage has this to say about immutable files: > > "A file with the 'i' attribute cannot be modified: it cannot be deleted > or renamed, no link can be created to this file, most of the file's > metadata can not be modified, and the file can not be opened in write > mode." > > This means that we need to flush the page cache when setting the nit: flush and invalidate the page cache. > immutable flag so that programs cannot continue to write to writable > mappings. Do we even need to invalidate the page cache for this? i.e. we've cleaned the pages so that any new write to them will fault, that will see the immutable flag via ->page_mkwrite and then the app should segv, right? > Signed-off-by: Darrick J. Wong > --- > fs/xfs/xfs_ioctl.c | 63 +++++++++++++++++++++++++++++++++++----------------- > 1 file changed, 43 insertions(+), 20 deletions(-) > > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > index 6ecdbb3af7de..2bd1c5ab5008 100644 > --- a/fs/xfs/xfs_ioctl.c > +++ b/fs/xfs/xfs_ioctl.c > @@ -998,6 +998,37 @@ xfs_diflags_to_linux( > #endif > } > > +static int > +xfs_ioctl_setattr_flush( > + struct xfs_inode *ip, > + int *join_flags) > +{ > + struct inode *inode = VFS_I(ip); > + int error; > + > + if (S_ISDIR(inode->i_mode)) > + return 0; > + if ((*join_flags) & (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL)) > + return 0; > + > + /* lock, flush and invalidate mapping in preparation for flag change */ > + xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); > + error = filemap_write_and_wait(inode->i_mapping); > + if (error) > + goto out_unlock; > + error = invalidate_inode_pages2(inode->i_mapping); > + if (error) > + goto out_unlock; > + > + *join_flags = XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL; > + return 0; > + > +out_unlock: > + xfs_iunlock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); > + return error; > + > +} Doesn't wait for direct IO to drain. Wouldn't it be better to do this? lock() xfs_flush_unmap_range(ip, 0, XFS_SIZE(ip)); unlock() Otherwise looks ok. Cheers, Dave. -- Dave Chinner david@fromorbit.com